Rope



Feb. 21, 1928.

ROPE

Filed Jan. 2, 1927 w I71 U6 71 '0 1 Ellis w. Brewster MM Mr- 2' J Q'xtta2 22296" 1,660,065' E. W. BREWSTER I 515 lay,

Patented Feb. 21, 1928.

UNITED STAT S ELLIS W. BREWSTER, OF PLYMOUTH, M

ASSACHUSETTS, ,ASSIGNOR TO PLYMOUTH COBDAGE COMPANY, OF NORTH PLYMOUTH,MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

ROPE.

Application filed January 22, 1927. Serial No. 162,898.

This invention relates to improvement in rope. More particularly itprovides an improvement in ordinary rope; that is, in rope consistingwholly of long and strong vege- 6 table fibres such as hemp or sisal.The invent-ion resides in the discovery of a articular arrangement of"elements by w 1i ch utility, strength, flexibility and durability arevery considerably improved as compared 10 with rope made from the samematerial according to standards generally accepted as ood. It is onefeature that the invention permits .of rope being made with a relativelysofter and therefore with greater strength, than heretofore; whilemaintaining in the strand a sufficient stability of form and asufficient resistance .to surface abrasion. In this respect theinvention 'both preventsba'clg'kinking, which is .particularly liable too'ccur in aloosely laid rope, and provides greater strength per v rope.It has been. found in practice that such a rope has longer life, ascompared with a 2 rope of equal diameter but of standard 'con-'struction, and that'it retains greater strength than is customary withstandard rope after any lmeasure of service which may have been adoptedfor comparison. Also, for reasons whichare incidental to its structure,the rope .of the invention is easier to splice, iseasier to handle whenin service, and is subject to less liability of being damaged byunskillful handling as by being drawn from a coil inthe wrong wa' By itssuperior stability it enables'the ubricant within it,

the strengtli of fibre, and the other characteristics of the rope toperform their several functions to better advantage, thus insuring 40that at any paricular instant arope thus constructed will be in bettercondition than a rope of" former standard construction would be, forwhatever service may be demanded of.it'.-

.These objects are strands together with a relatively soft lay,ginmakin'g the rope, andarranging yarns m .a special manner in thestrands, the yarns being made from hemp or other long fibre in. '60 theusual. way. The said arrangement is that some'of the yarns constitute acore and others of'them a cover for the core, with the yarns in the corelaid in a different direction from the Iayof the yarns in the cover.Preferpoundof hemp in the.

attained by putting" the ably also the twist of the individual yarns inthe cores is opposite to the twist of the individual yarns inv thecovers. The pitch of yarns in core and in cover may be equal or diverse,but the difference in directionof lay prevents the outside yarns fromever being drawn into the valleys between yarns of the core when afinished rope is twisted reversely. As neither untwisting nor furthertwisting of. such a soft laid rope will seriously disturb the structureof any of the strands, the rope can easily resume its normal structuralform after any such chance twisting. The individual twist of the yarnsat the surface can be as hard as desired.

It is intended that. the patent shall cover, by suitable expressioninthe appended claims, whatever features of patentable novelty exist inthe invention disclosed.

In the drawing:

The figure is a side elevation of a rope embodying the invention withone end unlaid to indicate construction, and the relations of fibres andyarns within.

Referring to the drawings, the three strands 10 of the specimen ropechosen for illustration. are laid together by twisting them in ordinarymanner, except that the lay is preferably soft, that is, with a pitchlonger than What has-hitherto been considered normal or necessary forthe particular size and kind of rope. Each strand 10 is homogenous, inthat it is is composed wholly of long vegetable fibres, such as hemp.These fibres are grouped in yarns 14 which are individually twisted. Asillustrated in the figurethe yarns in each strand are arranged in twogroups, one of which,;12,'includ1ng 12', is twisted as a group in onedirection, herein being called a core," while the other, 16, herein.called a cover, is laidin a sheath around the core 12 in a directionopposite to the twistof the core. Preferably the relative-pitch of thesetwo twisted groups may be such that when the rope is stretched thefibres in each group will reach their breaking-tension" at about thesame distance of stretch of the rope; as a whole. The -describedconstruction provides a rope'which has in the interior of each strand asubstantial body 12-of yarns with lay in the same direction as the layof the strand in the rope; and has exteriorly in each strand av body ofcover yarns whose lay everywhere.

crosses the lay ofthecor'e yarns and is oppo 1 site to the lay of thestrands. -When the rope is put into use rand by tension is stretched,the tightening-of 'the cover yarns may compress. the core severely.. Butthe core affords a,fir1nresistance,being-ofthe same material as thecover werelaid' in the same direction as the cover, or as mighthappen ifthe core were made of the same material as the cover but with varns laidparallel and straight. In the last mentioned case the core yarns wouldbecome taut and would break before the cover yarns had reached theirbreaking stress producing a rope of weak ultimate strength. And in thecase where all yarns in a strand are laid in a like direction, anyuntwisting of the rope such as sometimes arises in handling or in use,mightso. tighten the'twist of the cover yarns,

upontheir core, as to draw some or other of the outer yarns in betweenadjacent core yarns with Which-they are lying parallel.

This makes back-kinking which is a serlous evil because it spoils therope, and which is always possible in ordinary'rope because when outerand inner yarns are laid in the same direction back twisting of thegropeas a rotation in the twist applied, The danger whole tightens the outeryarns more than, it does the inner yarns per degree of angular of suchback-kinking is one reason Why the lay of ordinary rope is made sotight, and why it.cannot safely be made more soft as would be desirablein order to utilize a greater" proportion of the strength of the fibers.But in a'rope of the inventioneach strand has permanent stability ofform notwithstanding severe nntwi'st lng ofthe rope,

,and notwithstandi-ng abnormal; twisting of r it, for no 'amount'oftwisting or untwlsting the valley between two adjacent yarns-in the 1can move any yarn in the cover of the strand so that it comes intoparallelism with core thereof.- The cover yarns inevitably pass fromcrest to crest of the outer yarns 'of the core. However tight thecoveryarns be drawn, by an untwisting of the rope, or however much theybe relaxed by a twisting of the rope (which act holds the core yarns,the more firmly in shape) they arein each ,case sustained on thisinterior support of rounded crests. Other advantages follow. Thus,'asurface of cleavage whereon slip can easily occur, and 'which may ifdesired be themselves in proper position. they can, if. desired, runwith less pitch,-

- desirab specially ldhricated, is-provided in the midst of .eachstrand, and this makes-for flexibility of the completed rope. Inasmuchas the cover yarns are firmly binding the core yarns in their laidrelations, the core y'arnsdo not have to be twistedso-tightly in orderto hold Therefore more nearly longitudinally of the rope; or they may,as shown,.be ofa pitch approximating equality with the pitch of thecover yarns; or they may have greater pitch. .The yarns 14 arerepresented as being individually twisted-all in one direction in thecore 12, and all in the other direction in thecover 16. The interiorgroup of yarnsl2 in the coreis preferably twlsted with the caseillustrated all of them together do not make as many yarns as are. inthe cover. This, however, is a matter to be given congroup of core yarnssurrounding it, as in the sideration when anyparticular'rope is designed, and-if the interior body 12' were so large that the dangersindicated above were liable to arise, the remedy indicated. hereinshould be applied by reversing their direction of lay with respect tothe outer yarns 12 of the core. In case of a strand having such a secondreversal of direction of lay for its interior yarns, those yarns whichconstitute the outside layer of the core make a slip cover or sheathover the said reversed yarns within them, and a second surface ofcleavage between yarns is thus provided, en

hancing flexibilityof rope and, as, above de scribed, further preventingany back kinking arising by-inter-engagement of interior yarns incase-the rope as a whole is untwisted In the making of the rope theyarns 14; are made according to ordinary methods of suchmatei'ial ormixture and of such size and degree of twist as may be considered e; andthen for-the making ofthe core 12 a bundle of such yarns is twisted, sothat its'yarns are, for example,-laid to the right, using machinery ofany suitable type operating upon principles already known. Over thiscorethe cover yarns are laid in the opposite direction. For ordinarypurposesthis would complete a strand, 10.

The threeestrands 10,- or whatever other number of strands is to beused,may then be twisted together to make a rope-in the usual manner,preferably (laid at a pitch which is longer than .what is consideredsafe and necessary inrope made for the same duty but of the type atpresent standard in the rope industry.

This softness need -not result in dangerof greater surface abrasion, forthe cover yarns may bemade' with individual twist hard enou' h to resistsuch. 5 v

Nor nee the softness of lay result in a slipping between fibres of thecore and a disseminated throughout the whole body of.

the core, by a less intense constriction of the cover than if the fibresof the core lay all in parallelism with each other in one large mass.The force imparted at the surface of the core by the constriction ofcover yarns 'upon it is transmitted throughout the core more readily ina case, as here, where a concentration of the core can occur by slightcross slip of yarn upon yarn, laterally, and then the frictional holdingof fibre upon fibre, increased by this concentration, is aidthe localtwist of the fibre in its own yarn, all tending to prevent the fibresfrom slipping longitudinally upon its adjacent fibres. Thus each fibrebecomes capable of contributing to the rope whatever strength ,it hasregardless of slip or weakness which may occur in ,some other part ofthe core. This point being safeguarded it follows from the greaterlength of pitch of strands (softness of lay) which thus becomespermissible that the resultant or average lines of all fibres and yarnsbecome more nearly parallel to the axis than in the type of ropeprevaili'ng hitherto. 'Therefore, when the rope of the invention isunder. tension, the stress of fibres resultin from a given total tensionis less than is t e stress of fibres in a rope of ordinary construction,wherein the angle of strands to the axis is greater. And this producesthe consequence that the new rope as a whole in a given duty puts less130135101131 'strees on its fibres, and is stronger, size for size,besides having greater flexibility, and being secure against kinking. Byway of confirmation of this and as a further advantage, it has also beenobserved that experimental rope, embodying the invention and used forrtain work through a period equal to the life time of an ordinary ropein that service,

I claim as my invention:

1. A rope composed of a plurality of strands twisted together, each ofsaid strands having a core of yarns of long vegetable fibres, said yarnsbein twisted together, and a cover of yarns of laid around the core indirection opposite to the twist of the core.

2. A rope composed of a strands twisted together, each of said strandshaving a core of yarns twisted together and a cover of yarns twistedaround the core in direction opposite to the twist of the core the saidyarns in core and cover being sevplurality of s is at the end of theperiod still in good condition.

long vegetable fibres erally coinposed of long vegetable fibres twistedtogether to make the several yarns; the twist of individual yarns in thecore being opposite in direction to the twist of individual yarns in thecover.

3. A ropefcomposed of a plurality of ELLIS w. BREWSTER.

